Study on direct catalytic isomerization-disproportionation of turpentine by gas chromatography-mass spectrometry

The reaction products of turpentine synergetic catalytic isomerization- disproportionation at 120 degrees C over Pd/C-H2SO4 catalyst were analyzed and identified by chromatography and gas chromatography/mass spectrometry-data system(GC-MS). 45 peaks were separated and 37 compounds were tentatively identified. The main products were p-cymene (monocyelic monoterpenoid), carane (double ring monoterpene) and the main by-products were camphene, fenchol, limonene, borneol, eis-1-methyl-4-(1-methylethyl)-cyclohexanol, carene, isoborneol, p-menthan-8-ol, 2, 6-dimethyl-3-octene, which their relative contents were 51.42%, 27.62%, 4.65%, 2.29%, 2.28%, 1.25%, 0.46%, 0.38%, 0.37%, 0.35%, 0.33%, respectively. The analysis results showed that the isomerization and intermolecular hydrogen transfer disproportionation of bicyclic terpene pinene ( the main composition of turpentine) were main reaction. Simultaneously, some accompanying side reactions such as further ring-opening isomerization, aquated rearrangement reaction were occurred. And very few isomerization of sesquiterpene have been observed. 99.14% conversion of pinene and 57.46% selectivity for p-cymene were obtained.